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TCP/IP (including UDP) is a protocol. Are you just trying to find common things to allow for outbound internet access?
–
TheCleanerMar 17 '11 at 17:55

3 Answers
3

There are a lot of measurements of Internet traffic. I would suggest you start by searching for "internet traffic statistics" at Google scholar and start reading. Some articles to start with are the following:

If all you are wanting is to setup an outbound internet filter for your company here's my suggestion (since every company is unique).

Setup the default policy to allow any/any outbound. Enable logging of the traffic, preferably to a syslog server or something that can actually analyze the traffic and report on it (get a 30 day eval of something if you have to).

After letting it run for a few weeks, look at the traffic outbound...again preferably by reports, and then setup a new policy called "Allowed Internet Outbound" and add the protocols/ports/applications needed into it and then enable that policy and disable the original default policy.

The couple of weeks of reporting should also show you what to NOT allow outbound and who is abusing bandwidth.

The most popular ones would be listed in /etc/services in any modern *nix box if you have access to that. What are you attempting to do exactly? In securing an office environment for example, you would probably be better served filtering everything and allowing only what is needed, etc.